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  <script>
    //11. 检测昵称是否是有汉字字母数字下划线组成，6-8位
    let str = prompt("请输入内容");
    let reg = /^[a-zA-Z\d\_\u4e00-\u9fa5]{6,8}$/
    if(reg.test(str)){
          alert("true");
    }else{
        alert("false");
    }
  </script>
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